Many projectiles include fins that are used to maneuver the projectile during flight. The fins are usually adjusted using some form of adjustment mechanism.
Many adjustment mechanisms typically include a gear system that is engaged with a drive that turns the gears. The gears are also engaged with the fin such that when the drive turns the gears, the fin is adjusted.
One of the drawbacks with existing adjustment mechanisms is that they are typically be designed and manufactured with tight tolerances and stiffer designs which make them relatively expensive to produce. The expense can be significant because the gears in existing adjustment mechanisms need to be run-in and measured in a variety of environments.
During flight of the projectile the fins are placed under relatively high aerodynamic loads when the projectile needs to be maneuvered by the fins. A fin maneuvers the projectile by moving from a neutral state (where the aerodynamic load is at a minimum) during flight in one direction or another depending on which way the projectile needs to be maneuvered.
The tight tolerances of existing adjustment mechanisms within the projectile can be problematic when the fin is placed under relatively high aerodynamic loads during flight. The combination of a relatively high aerodynamic load on the fins and overall tightness of the gears in the adjustment mechanism often causes the adjustment mechanisms to bind up during operation. The binding up problem is not as great when the fin is in a neutral position during flight because there is a lower aerodynamic load.